Glass-ceramics have useful properties for both passive and active photonic applications which are difficult or impossible to achieve in glasses or other materials. One such property is a negative thermal expansion coefficient, which is useful in athermalization of fiber Bragg gratings, devices that can be used in a variety of optical components such as narrow band filters. Transparent glass-ceramics can display similar luminescent properties to those of single crystals, yet can be fabricated into fiber form with rapid glass-forming techniques. Rare-earth-doped fluoride nanocrystals have been precipitated in oxyfluoride glass-ceramics with resulting luminescent efficiency superior to those of less stable RE-doped fluoride glasses. Recently, transition metal-doped glass-ceramics, particularly CR: forsterite, have demonstrated broad near infrared luminescence with similar characteristics to those of single crystals. Fiber lasers and optical amplification devices are envisioned.
